Process and apparatus for acid treating light mineral oil



y 93 F. o. BLAIR 2,001,899

PROCESS AND APPARATUS FOR ACID TREATING LIGHT MINERAL OIL Filed Dec. 11,1929 Ewe/72157": Funk 0 Blair Patented May attract PROCESS AND APPARATUSFOR ACID TREATING LIGHT MINERAL OIL Frank 0. Blair, Laramie, w'yd,Standard Oil Company, Chicago,

' ration of Indiana assignor to 111., a com- Application December 11,1929, Serial No. 413,351

5 Claims.

.This invention relates to an apparatus and a process for treating onand it pertains more particularly to the treatment of pressuredistillate with sulfuric acid for the removal of unsaturated 5hydrocarbons, gum forming resins, coloring matter, etc.

Pressure distillate is the gasoline fraction obtained from crackingstills, and is characterized by its tendency. to standing.

discolor and form gums on To remove the unsaturated hydrocarbons andmaterials responsible for this deterioration the pressure distillatemust be subjected to a small amount of used up in this process 'sary totransfer th a treatment'with sulfuric acid., Only the *treating acid isactually and it is therefore necese sludge to an acid plant forrecovering and restoring. the unused acid remaining in the sludge.

The hydrolyzing, separating and restoring of the sludge acid isobjectionable and difiicult because of the corrosive natiire of thematerials, because of the amount of equipment, time, labor and expenserequired and because of' the unavoidabl which are'wafted parts of therefinery, corroding expose parts and depleting e sulfuric anhydridefumes from the acid works to all d metal the health and efliciency ofthe workmen. The object of my invention is to overcome all of theseobjectionable features and to eliminate the acid recovery plantby'providing a process in which the treating acid is almost completelyutilized.

i A further object is to provide a process for treating pressuredistillate in which tion of acid is materially the consumpreduced and inwhich the cost of equipment and operation is likewise minimized.

A further object is to provide a new and improved arrangement ofapparatus whereby pressure distillate may be treated by my improvedprocess.

Other objects will be apparent as the detailed description of myinvention proceeds.

My invention contemplates a process in which pressure distillate is intoa settling tank until a quanaccumulated in said tank. Larger anddischarged tity of sludge is treated with sulfuric acid quantities ofthe accumulated sludge from this tank are then used instead of sulfuricacid for the treatment of further quantities of pressure distillate, themixture second settling tank.

until the sludge from used up at which time used in still tank ispressure distillate,

being discharged into a This process is continued the first tank isentirely the sludge'from the second larger quantities to treat themixture being introduced into the first separating creasing pressuredistillate ineach step, ve or polymerize effectively remo unsaturatedhydrocarbons,

there is no necessity of recovering or trating it. The final sludgecontains practically no free acid and it consists almpst entirely ofhydrocarbon derivatives of be burned as a fuel. contain from the hydrocgives the tests for free acid In the accomp y drawing, diagrammaticallyan arrangement 1 for carrying out my improve Briefly, incoming pressurebeen carefully dried, is mixe By gradually inthe amount of sludge usedto treat the that I can all objectionable and at the same time 5 I canutilize the acid to such an extent that reconcensulfuric acid. It mayThis slud'ge, howevendoes combined acid whiclr may be separated arbonradical by-hydrolysis and if mixedwith water.

ave shown apparatus d process.

distillate,

which has d with acid from tank A in prifice mixer 18, settled in tank 0pr D and finally washed and treated in tanks E and F1 Additional drying,washing may be required for various tillates and I contemplate the oilsor apparatus and processeswhich are those skilled in this art.

Pressure distillate is tank through pipe I regulated by valve l2,through pipe l3 to a M. This mixer may conhole or orifice mixer sist ofa cylindrical casing I of baflle'plates IG -mounted plates having small5 having use of any,

and/ or treatin tanks pressure disand all known to 25 pumped from astorage 0 by pump" in quantities knota plurali y therein, each of said Lholes at their center so that liquids forced therethrough at highvelocities will 1 circulate in the spaces duce a thorough and uniformThe acid used in. my process between the plates'to 'mixture.

pro-

is pumped from storage tank A through pipe l1, valve l3 and pipe l3 bypump 20 through regulatingvalve 2|, pipe 22 and pipe I3 to the orificethoroughly mixed with the pressure above described.

mixer B where it The acid mixture is conducted through conduit,

23, valve 24 and pipe 25 to sludge rapidly settles to the and thetreated pressure through pipe 26, valve 21 and pipes to a point adjacentthe bottom of washing settling tank C. Th

bottom of this tank distillate is discharged 23 and 23 tower-E wherewater from a suitable source is supplied, through the treated throughpipe 30 and sprayed material by nozzle 3|.

The waterand impurities washed out of the treated distillate may be remo32, valve 33 and pipe 34. The wash is transferred from the top oftowerved th ou h r pe ed distillate any pipe-f to a point near the bottom oftreating tank F where a doctor solution is introduced through pipe 3tand sprayed through the washed distillate by nozzle 3']. The treatingliquid is removed from the bottom of tower F through pipe 38, valve andpipe fill, the sweetened distillate being transferred by pipe G ito asuitable storage tank.

It is understood that any number of washing -or treating towers may beused and that additional towers may be used for drying the distillate asis well known to those skilled in the art.

When the tower C, which is preferably about ft. in diameter and it.high, has accumulated a sufiicient amount of sludge (when 22,500 poundsof acid have been used to treat 6000 barrels of pressure distillate) thevalve 118 is closed and instead of using acid for the treatment ofincoming pressure distillate, sludge is withdrawn from the bottom oftower 0 through pipe d2, valve 13, pipes 36, t5 and it? by pump 28 andis discharged through valve 26 and pipes 22 and 82 to the orifice mixer13'. At the same time valve 2d is closed and the orifice mixerdischarges through pipe 23, open valve GE and pipe ll to the secondtreating tower D, the treated pressure distillate being dischargedthrough pipe 38, valve (it and pipe 29 to the washing tower E as abovedescribed. Sludge is now accumulated in separating tank D.

When the treated sludge from tank C has been transferred to tank D,valve (is is closed and sludge from tank D is pumped through pipe 56,valve 5i, pipes 5 and it by pump 20 through valve 2! and pipes 22 andit! to the orifice mixer which discharges again into tower C, valve 26being opened and valve 45 being closed.

' For the first treatment when fresh acid (about 59 Be.) is used and.about 4 pounds of acid will be required per barrel of pressuredistillate treated, valves 53, 4G, 49, and 5! being closed. After 6000barrels of pressure distillate have been treated, valves I8, 24, and 5!are clwed and valves 43, 46 and 49 are open, the sludge from tank Cbeing mixed with incoming pressure distillate at I the rate of about 5pounds per barrel. When the sludge from tank C has been entirelytransferred to tank D, valves 43 and 46 are closed and valves 2| and 5|are opened, and the sludge from tank D is mixed with incoming pressuredistillate at the rate of about 6 pounds per barrel. After this iscomplete valves 24 and 50 are closed and valves and 46 are opened, thesludge from tank C being mixed with incoming pressure distillate, usingabout 7 pounds per barrel. About two more treatments of 8 and 9 poundsper barrel respectively will sufficiently utilize the acid in the sludgeso that it may then be run to a suitable storage tank by a. conduit (notshown) for use as a. fuel 'or for the recovery of organic compoundsformed by the treatment. The amounts of acid, as above stated, refer tothe active acid content 'of the sludge. The volume of sludge will bedependent on the amount of impurities removed, and in the finaltreatment, the volume of sludge per volume of oil treated may be tentimes the originalvolume of'acid used.

While I have shown two treating tanks, C and D, it is understood that Ido not limit myself to this system. I may use a single tankandcontinuously remove the sludge from the bottom 7 thereof, supplyingit in increasing amounts to the fresh pressure distillate. Again, I mayrun the sludge to separate tanks and use it as needed therefrom. It isonly essential that I increase the amount of the treating reagent as theacid content of the sludge is depleted, and that I aooreoo utilize theacid to such an extent that its recovery is rendered uneconomical andunnecessary.

While I have described a process for treating pressure distillate, itwill be evident that the process is applicable to the treatment of otherhydrocarbon oils and I do not limit myself to any particular chargingstock.

It is important for the successful operation of my process that the oilor pressure distillate be thoroughly dried before it is introduced intothe orifice mixer because the treating acid is inefiective in dilutesolutions. The temperature of the treatment should preferably bemaintained at about 70 F.

The sludge at the end of the cycle has about the following properties:

(100 gal. sludge equivalent to 62 gals. of fuel oil.)

Chemical composition Per cent Water 6.62 H2304 (in combination) 33.? Oil(in combination) 40.3

The method above described cutsdown the total acid consumption to aboutone-fourth of the normal amount, but it should be noted that in thisprocess each barrel of oil is actually contacted with as much or moreacid than by the old method, thus giving a better product. My processcontemplates the re-use of sludge on untreated oil until the free acidin the sludge is substantially utilized. The cost of treatment ismaterially reduced, the corrosive and disagreeable sulfuric acid gasesare eliminated and a better and more stable product is produced.

I claim:

1. In apparatus of the class described for treating mineral oils, aplurality of settling tanks, a mixer, a means for supplying oil to saidmixer, means for supplying a. treating agent to said mixer, selectivemeans for transferring a mixture of oil and treating agent from saidmixer to either-of said tanks, and selective means for returning settledmaterials from either of said tanks to said mixer.

2. In combination for mineral oil refining, a mixer, means for supplyingoil to said mixer, means for supplying a, treating fluid to said mixer,a. pair of tanks, selective means for transferring fluids from saidmixer to either of said tanks, selective means for returning liquidsfrom the bottom part of said tanks to said mixer, and means for removingtreating fluids from the treated oil discharged from said pair of tanks.

3. The process of acid treating a. light mineral oil which comprisesthoroughly mixing and agitating said oil and sulfuric acid sludge,passing said mixture of oil and acid sludge to a settling zone where thesulfuric acid sludge is permitted to settle, removing the settledsludge, thoroughly mixing and agitating said settled acid sludge withanother portion of untreated light mineral oil, the amount of sulfuricacid sludge being greater than the amount used in the first treatment,passing the second mixture of sulfuric acid sludge and .oil to a secondsettling zone where the sludge is again permitted to settle, and re-'moving the, used sulfuric acid sludge from the t eated 01L l UM 4. Theprocess of acid treating pressure distillate oils which comprisesthoroughly mixing and agitating said oil and sulfuric acid sludge,passing said mixture of oil and acid sludge to a quiescent settling zonewhere the sulfuric acid sludge is permitted to settle, removing thesettled sludge, thoroughly mixing and agitating said settled acid sludgewith another portion of untreated pressure distillate oil, the amount ofsulfuric acid sludge being greater than the amount used in the firsttreatment, passing the second mixture of sulfuric acid sludge and oil toa second quiescent settling zone where the sludge is again permitted tosettle, and removing the used sulfuric acid sludge from the oil.

5. The process of acid treating a light mineral oil which comprisesthoroughly mixing and agitating said oil and sulfuric acid sludge,passing said mixture to a settling zone where the sulfuric acid sludgeseparates from the treated oil, removing the settled sludge from thetreated oil and then thoroughly mixing and agitating said sludge withanother portion of untreated light mineral oil, the amount of said acidsludge being

